1. Field of the Invention
This invention relates to a device for cleaning a mandrel of an extrusion press.
2. Description of the Prior Art
The extrusion press which is resorted to for metal extrusion generally includes a container for holding a billet, a pressurizing stem for pressing the billet in the container toward a die, and a mandrel fitted in the pressurizing stem axially slidably relative to the latter to thereby restrict the internal shape of a hollow metal structure which is extruded through the die. In an extrusion press of this sort, cleaning of the mandrel every several or more pushes is required in order to remove metal shells which deposit on the mandrel in considerable amounts. Automation has been achieved with respect to those component parts of the press which are required in the sequential phases of each cycle of extruding operation, namely, which are required for the feed of a billet, piercing, extrusion, shearing, discard dummy block handling and the like, in contrast to the mandrel cleaning operation which still depends on manual labor. The manual cleaning operation which not only imposes a great burden on the operator but requires him to step into the press is problematic from the standpoint of safety of operation. In this connection, the conventional practice has been to use a jig with a split flange which is adapted to grip the mandrel in its flange portion and scrape off the shells utilizing the movement of the mandrel itself. However, a problem is encountered with the conventional device in that the flange portion is often pushed apart depending upon the shell condition, failing to remove completely the shells which might seriously affect the quality of the extruded products.